1. Field of the Invention
The present invention relates to a mobile communication terminal, and more particularly to a mobile communication terminal with a non-contact communication function for wireless communication at close range.
2. Description of the Related Art
These days, a technology is widespread for conducting wireless communication at close range utilizing, for example, a non-contact type IC card to carry out user authentication and to transmit/receive information. JP 2004-56413 A discloses a technology where a mobile communication terminal such as a mobile phone conducts the above-mentioned close range wireless communication. More specifically, a mobile phone can have a user identity module (UIM) attached thereto. The UIM has an IC chip, a loop-like antenna coil, such as a loop antenna coil, and the like for close range wireless communication. The antenna coil may be attached to the mobile phone in advance. A user of the mobile phone can use the mobile phone for user authentication, entrance into (or exit from) a specific place, transmittance/reception of information with an external device, and the like.
The UIM is disposed far from a display portion of the mobile phone to keep out of the way of the display portion. It follows that the UIM is proximate to a user's hand which operates a key operation portion. A hand or fingers of the user who grasps the key operation portion degrade antenna characteristics and decrease the sensitivity of the close range wireless communication. In close range wireless communication, a magnetic flux which passes through a center portion of the antenna coil generates induced electromotive force for conducting wireless communication. In order to improve the sensitivity of the wireless communication, it is necessary to, for example, make as much magnetic flux as possible pass through a cross-section of the antenna coil. However, the antenna coil attached to the UIM is an antenna coil having a relatively small cross section. Therefore, the amount of magnetic flux which passes through the center portion of the antenna coil is limited.